The prior art is recplete with various roller assembly constructions intended for mounting under a boot foot plate to form a roller skate. Conventionally, such roller skates utilize a pair of laterally aligned front wheels and a separate pair of laterally aligned rear wheels.
In recent years, in-line roller skates have become extremely popular. Such skates generally use three to five identical wheels supported in alignment. Typically, such wheels have about a 2.75 inch (70 mm) diameter with the respective laterally oriented wheel axles being longitudinally spaced by about 3 inches. The axles are typically aligned about 2 inches beneath the foot plate so that a flat ground surface is tangent to all of the wheels. However, many models of in-line skates include a "rocker capability" enabling a user to lower the position of the center wheels, relative to the front and rear wheels. For example only, sec U.S. Pat. Nos. 5,048,848 and 3,880,441.
In-line skate wheel rocketing is intended to simulate the arcuate bearing surface provided by an ice hockey skate rocker blade to improve maneuverability. However, whereas a rocker blade presents a continuous arcuate bearing surface, wheel rockering can only roughly simulate this continuous surface since it is essentially defined by straight line segments between discrete wheel contact points. More particularly, when the wheels are in the rocker position, the user's weight will usually be supported on the two center wheels, but in the course of skating, will typically move to (1) the front and front center wheels or to (2) the rear and rear center wheels. In going through such transitions, the user's weight for short intervals will be supported on only a single wheel. This therefore requires that each wheel and its associated axle and bearing structure be designed to readily support the full weight of the user to avoid introducing excessive frictional drag. Moreover, when in the rocker position, the user's foot plate is supported only on the short span between adjacent wheels, thus reducing skater stability in favor of enhanced maneuverability. However, wheel rockering still docs not yield the full maneuverability advantages offered by the continuous curve of a rocker blade since it merely simulates an are by spaced discrete wheel contact points.
In addition to the aforementioned conventional and in-line skates, endless tread skates have also been known for many years. Exemplary U.S. patents include U.S. Pat. Nos. 342,458; 675,824; 889,946; 1,694,162; 2,412,290; 3,671,051; 4,572,528; 4,627,630. Exemplary foreign patents include UK Patent 422,633 and Australian patent 135,274. These endless tread skates utilize a flexible belt or chain which travels around and conforms to a defined path, typically formed by a plurality of wheels or rollers, to essentially lay down a smooth track for the rollers. Although the path defined by the rollers can be arcuately shaped, nevertheless since the flexible belt conforms to the path, and is not designed to be weight supporting, a user's weight will still be supported on only one or two rollers. Thus, the stability and maneuverability characteristics of such endless tread skates would be similar to wheel rockered in-line skates.